Digital light processing
How direct light processing (DLP) differentiates from other 3D printing technologies
Additive manufacturing technologies (AMT) are a fast-growing field of relatively new production methods which directly produce a three-dimensional part without using molds or removing material e.g. by milling.
Selective laser sintering (SLS)
With selective laser sintering (SLS) fine material particles are melted or sintered together by a laser beam. Advantages are that from polymers to metals all kind of materials can be used with this technique. Also, no support structures are needed but the price and handling of fine
powders is troublesome
Jetting technologies (JET)
Jetting technologies (JET) use low viscous resins or binders either to directly build parts or a binder is jetted on a powder bed, binding particles to a part layer by layer. Parts that are directly printed by jet systems or not sintered are always very brittle as the low viscous inkjet resins exhibit rather poor mechanical properties.
Fused deposition modeling (FDM)
In fused deposition modeling (FDM) polymer filaments are extruded through a fine nozzle and the part is built by lines of molten thermoplast. Great material properties can be achieved as usual thermoplasts as ABS can be used. The resolution is poor as the high viscosity of the polymer melt
In photopolymerization techniques light sensitive liquid resins are solidified by light irradiation. Areas which are irradiated solidify almost instantly. Mostly UV-light between 365 and 410 nm is applied through a window from underneath.
Using a laser beam which is scanning over each layer (SLA) offers high accuracy and high power density in the laser spot. But scanning over layers with a large area takes a lot of time and makes SLA printing relatively slow.
With UV LCD screens the whole printing area can be irradiated at the same time but the power of UV LCD screens is very limited. This results in long irradiation times and low printing speed.
Digital light processing (DLP)
Digital light processing (DLP) offers high power intensities and the possibility to irradiate the entire printing platform at the same time.
This makes DLP especially efficient. By combination of DLP with oxygen permeable windows exceptional printing speeds with high accuracy can be reached. All printers using photopolymerization, produce green parts which have to be cleaned of excessive resin and then post cured to archive the final mechanical propterties.